Influence of Magnesia-to-Phosphate Molar Ratio on Microstructures, Mechanical Properties and Thermal Conductivity of Magnesium Potassium Phosphate Cement Paste with Large Water-to-Solid Ratio


This paper describes the influence of the magnesia-to-phosphate (M/P) molar ratios ranging from 4 to 12, on the properties and microstructures of magnesium potassium phosphate cement (MKPC) pastes with a large water-to-solid ratio (w/s) of 0.50. The setting behavior, compressive strength, tensile bonding strength and thermal conductivity of the MKPC pastes, were investigated. The results show that an increase in the M/P ratio can slow down the setting reaction, and clearly degrade the mechanical strengths, but clearly improve the thermal conductivity of MKPC pastes. Furthermore, micro-characterizations including X-ray diffraction, scanning electron microscopy and thermogravimetric analysis, on the MKPC pastes reveal that a lower M/P ratio can facilitate better crystallization of the resultant magnesium potassium phosphate hexahydrate (MKP) and a denser microstructure. Moreover, strong linear correlations are found between the mechanical strengths and the MKP-to-space ratio, and between thermal conductivity and the volume ratio of the unreacted magnesia to the MKP.


Civil, Architectural and Environmental Engineering

Keywords and Phrases

Cements; Compressive Strength; Magnesia; Magnesium; Mechanical Properties; Microstructure; Phosphates; Potassium; Scanning Electron Microscopy; Thermal Conductivity of Solids; Thermogravimetric Analysis; X Ray Diffraction; Chemically Bonded Ceramics; Linear Correlation; Magnesium Potassium Phosphate Cements; Magnesium Potassium Phosphate Hexahydrates; MgO; Properties and Microstructures; Setting Reactions; Water-to-solid Ratios; Thermal Conductivity; Transport properties

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Article - Journal

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© 2015 Elsevier Ltd, All rights reserved.

Publication Date

01 Feb 2015